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DY: Fachverband Dynamik und Statistische Physik
DY 32: Poster: Active Matter, Soft Matter, Fluids
DY 32.15: Poster
Wednesday, March 20, 2024, 15:00–18:00, Poster C
Thermodynamics and coarse graining of colloidal heat engines with active baths — •Roland Wiese1, Klaus Kroy1, and Viktor Holubec2 — 1Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany — 2Faculty of Mathematics and Physics, Charles University, CZ-180 00 Prague, Czech Republic
We review the applicability of effective temperatures to describe the thermodynamics of a colloidal probe particle in a bath of active Brownian particles - a prototypical example of a non-equilibrium Brownian system. Using Brownian dynamics simulations, we realise a microscopic Stirling cycle by modulating the probe's trapping potential and the bath particles' swim speed. In contrast to claims for recent experimental studies of colloids in bacterial baths, we show that Carnot's limit for the thermodynamic efficiency cannot be broken, even for a strongly non-Gaussian active bath, by reproducing and rationalising the average performance reported for the experimental system. The probe-in-active-bath setup is coarse-grained to a single active Brownian particle (ABP) and to a single active Ornstein-Uhlenbeck particle (AOUP), with their respective noise correlations determined by the underlying probe-bath interactions. Not only thermodynamic averages but even the stochastic fluctuations of the exchanged work and heat are faithfully preserved for the AOUP.
Keywords: Stochastic thermodynamics; Heat engine; Stirling cycle; Non-equilibrium fluctuations; Effective temperature